1. Field of the Invention
The present invention relates to a lead clamping apparatus employed when an electronic circuit element, such as a dual in-line package type integrated circuit element, is inserted into a printed board which constitutes an electronic circuit.
2. Description of the Prior Art
A dual in-line package type integrated circuit element (referred to as a "DIP type IC", hereinafter) has a configuration as shown in FIGS. 1A, 1B and 1C. With the recent development of semiconductor technology, DIP type ICs are becoming the nucleus of the various constituent elements of electronic circuits.
First of all, conventional apparatuses for clamping leads which are employed when such DIP type ICs are automatically inserted into an electronic circuit board will be described hereinunder with reference to FIGS. 2 to 5.
The conventional lead clamping apparatuses may be roughly classified into two types, that is, the lead clamping type and the insertion guide type. In the lead clamping type apparatus shown in FIGS. 2 and 3, a DIP type IC 1 is first fed from a parts feeder unit (not shown) and is conveyed and transferred. The DIP type IC 1 then is caught by all of its leads 3 by means of integrated clamping members 2. After the distance between the leads 3 on both sides of the DIP type IC 1 is made to correspond with the distance, between two rows of insertion holes 4, 4 formed in an electronic circuit board 5, the leads 3 are properly positioned directly above their mating insertion holes 4. Thereafter, the DIP type IC 1 is pushed by a piston 6 in such a manner that the leads 3 are respectively inserted into the insertion holes 4.
In the insertion guide type apparatus shown in FIGS. 4 and 5, on the other hand, the DIP type IC 1 having been fed, conveyed and transferred in a manner similar to the above, is suction-held by a piston 7 having a suction surface by the operation of a vacuum device (not shown) and is mounted on the electronic circuit board 5 while insertion guides 8 placed closely to the insertion holes 4 on the board 5 guide the leads 3.
It will be understood from the above that both the lead clamping type apparatus and the insertion guide type apparatus must be capable of clamping and guiding a DIP type IC having a maximum insertable number of leads (6 to 22 pins for 0.3-inch DIP type IC). For this reason, when a DIP type IC having a smaller number of pins is inserted in the electronic circuit board 5, such apparatus always involves an unnecessary area (a dead space).
More specifically, as shown in FIG. 6, even when the electronic circuit board 5 has an area large enough for receiving a DIP type IC to be mounted thereon, surplus portions of catching members of the apparatus which are not used for catching the leads of the DIP type IC may interfere with parts or obstacles which have been previously mounted in the vicinity of an area on the circuit board where the DIP type IC is to be placed, so that it would be impossible to insert the DIP type IC into the circuit board.
When various kinds of electronic elements are to be mounted on one electronic circuit board, however, it is generally necessary to insert electronic elements in the vicinity of DIP type ICs in order to densely mount them on the board. In consequence, it is inevitable that when placing successively mounted elements the catching of the previously positioned members by the apparatus can be prevented of the electronic elements are placed on the board in such an order that the apparatus is prevented from interfering with the existing electronic elements on the board. For this reason, it is not possible to feed DIP type ICs in a predetermined cycle time, which fact leads to variations in the period of time required for insertion of DIP type IC into the board, resulting in troublesome arrangements for the insertion operation, such as preparation of an insertion program, as well as a low degree of freedom in designing the electronic circuit board. Accordingly, the above-described fact has been an obstacle to increases in production efficiency.
If priority is given to the feed of DIP type ICs in a constant cycle time, then it is necessary to insert the DIP type ICs into the circuit board prior to the mounting of other electronic elements, which disadvantageously constitutes a limitation in inserting elements into the electronic circuit board.